1. Triangles

2. Classifying Triangles
Vocabulary:
Triangle - A three-sided shape made up by the intersection of 3 lines.
Classifying Triangles
By Angle:
Acute Triangles- all angles are less than 90°.
Obtuse Triangles- has one angle greater than 90° and two angles less than 90°.
Right Triangles- has one angle exactly 90°.

3. Equilateral Triangles- all sides are congruent.
By Side:
Equilateral Triangles- all sides are congruent.
**Note- All angles are ALSO congruent.**
60°
Isosceles Triangles- TWO sides are congruent.
**Note- 2 angles will also be congruent.**
Scalene Triangles- has NO congruent sides.

4. bh Perimeter of a Triangle: Add all of the sides together. 1 ___2 bh
Area of a Triangle:

5. 2 cm
4 ft
3 in
2 in
9 in
3 m
7 in
1 m
8 in
2 ft
5 ft

6. Measuring Triangles Using Protractors

7. ALL OF THE ANGLES OF A TRIANGLE ADD UP TO 180°!!!!

8. Creating Triangles Based on Given Information
Draw and label a triangle where A=30°, B=60°, and C=90°.

9. Creating Triangles Based on Given Information
Draw and label a triangle where A=15°, B=75°, and C=90°.

10. Creating Triangles Based on Given Information
Draw and label a triangle where A=60°, B=60°, and C=60°.

11. If any of those are untrue, than it will NOT make a triangle.
Determining Triangles
If:
A+B > C
B+C > A
and
A+C > B
Then you have a triangle.
If any of those are untrue, than it will NOT make a triangle.

12. Will the follow create a triangle:
Side A= B= C=
3 in.
3 in.
3 in.
10 in.
4 in.
2 in.
2 cm
3 cm
4 cm
5 yds
3 yds
2 yds

13. Using Vertical Angles and Creating Triangles Worksheet
Vertical Angles are equal when made by straight intersecting lines.
Triangles should be labeled by their sides AND their angles.
ALL TRIANGLES ADD UP TO 180°!!!
Review:
HW:
Using Vertical Angles and Creating Triangles Worksheet